1. Field of the Invention
The present invention relates to a push switch constructed so that a stroke of a movable contact point arranged away from a stationary contact point is performed on an opposing line thereof to be in contact with each other, thereby closing an electrical circuit.
2. Description of Related Art
Japanese Patent Laid-Open No. 2005-149739 discloses this type of conventional push switches. This push switch is attached to a brake pedal for a vehicle, and an operation shaft pushed into a case of the push switch retains a movable contact point to be positioned away from a stationary contact point in an attaching state of the push switch. When the brake pedal is depressed, the operation shaft is moved in a direction outside of the case so that the movable contact point urged by a contact pressure spring is configured to be moved for being in contact with the stationary contact point. Here, the movable contact point includes two contact points an intermediate portion of which is urged by one contact pressure spring.
At the time of operating the push switch, respective opposing surfaces of the movable contact point and the stationary contact point vertically approach with each other or move away from each other. However, there occurs quite often a case where wear debris are produced between the opposing surfaces of the movable contact point and the stationary contact point or arc is discharged between the contact points caused by the operation of the push switch to deposit carbide or oxide therein, thereby forming an insulating film between the contact points. In consequence, this case may cause a so-called contact failure, thereby possibly creating an unstable operation of the push switch.
Therefore, the aforementioned conventional push switch is constructed so that immediately before the movable contact point gets in contact with the stationary contact point, a flexible member causes the movable contact point to move laterally to the stroke direction. In consequence, this lateral movement acts to perform wiping on the contact surfaces of the contact points with each other for removing wear debris, carbide, oxide and the like (hereinafter, collectively referred to as foreign matter).
The aforementioned conventional push switch is, however, provided with a contact pressure spring 15 for wiping the contact surfaces of the contact points and further, a flexible member 18 as a different member. In other words, the above conventional push switch needs two kinds of components, and is, therefore, high in manufacturing costs and also leads to an increase in managing costs after all.
The above push switch is configured in the form where when the operation shaft moves in a direction outside of the case, the movable contact point gets in contact with the stationary contact point, but the structure in which when the operation shaft (push rod) is pushed in, the movable contact point gets in contact with the stationary contact point raises also the similar problem.
In view of the above, there exists a need for a push switch which overcomes the above-mentioned problem in the related art. The present invention addresses this need in the related art as well as other needs, which will become apparent to those skilled in the art from this disclosure.